BIMI

BIMI (Brand Indicators for Message Identification) is way for an email client to verify the authenticity of a message. This works by checking your message, then adding a verified logo to your message. This allows your readers to know that your message is legitimate, and sent by your company.

To use BIMI, your logo must be trademarked (like, literally, with the USPTO), and you must have a DMARC policy of quarantine or reject. You must also have a valid DKIM signature on your message.

You can learn more here.